Wednesday 14 October 2015

HURRICANES AND TORNADOES

HURRICANES AND TORNADOES

What are Hurricanes, Cyclones and Typhoons?

Hurricanes, Cyclones and Typhoons are all the same weather phenomena. They can be defined as violent low-pressure systems in which the central core is warmer than the surrounding winds. They all have strong rotating or swirling winds, lightning, thunders, lots of rain and low pressure. The difference between them is given by the location in which these phenomena take place:
•In the Atlantic and Northeast Pacific, the term hurricane is used.
•The same type of disturbance in the Northwest Pacific is called a typhoon
•Cyclones occur in the South Pacific and Indian Ocean.


What are Tornadoes?

A tornado can be defined as a destructive and dangerous windstorm whose clouds are shaped like a funnel. The funnel or whirlwind extends from the bottom of a cumuliform cloud to the ground and moves over land and destroys everything in its path. Not all tornadoes are visible as funnel clouds.
The Fujita Scale is a scale that tells how severe a tornado is based on wind speed and damage being caused.

Where do they take place?

Tornado Alley: an area in the western portion of the US that runs from the western side of Texas up to North and South Dakota, known for its many tornado strikes. This is an area prone to tornadoes. However, this does not mean that tornadoes cannot take place elsewhere; in New Zealand, Australia, South America, Africa and Eastern Europe tornadoes have occurred. 
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Similarities and Differences between Hurricanes and Tornadoes

In the structure of both a hurricane and a tornado, there is a relatively calm, clear area at the center. Winds blow in a spiral around this roughly circular center called the eye. Both tornadoes and hurricanes contain strong rotating winds that can cause damage.
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Causes of Tornadoes

The truth is, there is still a lot we don’t know about how tornadoes form. The conditions that may give rise to one tornado won’t necessarily cause another. But the most likely possibility of forming them is a thunderstorm; but not any thunderstorm. Just the ones that have sufficient instability and wind shear present in the lower atmosphere; they are called “supercells.” 
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Instability refers to unusually warm and humid conditions in the lower atmosphere, and possibly cooler than usual conditions in the upper atmosphere. Wind shear in this case refers to the wind direction changing, and the wind speed increasing, with height. Winds near the surface blow in one direction, while winds above blow in another direction. The difference between them creates a horizontally rotating mass of air. Rising warm air creates an updraft, pulling the rotating air upright.
Now the thunderstorm forms a rotating vortex, or a mesocyclone that then creates the funnel cloud. Most researchers believe that the funnel starts from above and drops down to a region where the air pressure is lower.

 
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Effects of Tornadoes

  • Loss of Life: Tornadoes typically kill 60 to 80 people per year and injure more than 1,500. Most deaths come from flying or falling debris, and occur in the most violent tornadoes, which account for 70 percent of tornado deaths.
  • Property Damage: Another significant effect tornadoes have on humans is the property damage. Weak tornadoes can take the roofs off buildings and break windows. Stronger tornadoes have been shown to destroy entire buildings.
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A  house after a tornado hit Ocklahoma in May 2013
  • Effects on Nature: Trees and plants can be uprooted, and diseases in the soil are spread. Wildlife loses their lives or habitat. Their effects on the environment are not just restricted to uprooting of trees though, but go well beyond that - as they also contribute to environmental pollution. This environmental pollution can be attributed to the huge amount of dust that these tornadoes bring in from dry regions, flying debris of structures brought down by them, etc. Even the fluid that is leaked from the vehicles; which are reduced to junk by tornadoes, contribute to environmental pollution by polluting soil and water.
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Preventive Measures

There are simple ways to prepare and keep safe before and during a tornado.
Before the tonado
  • PUT TOGETHER A FAMILY EMERGENCY PLAN: Discuss with your family how to get to a safety place, how to communicate with one another, and where are you going to meet after the event is over. Find out where local shelters are and the fastest way to get there. Practise periodic drills so that you and your family members know what to do if a tornado warning is issued.
  • PREPARE AN EMERGENCY KIT: It should help you and your family get by without heat or electricity for at least 72 hs. Use a bag or cardboard box and pack it with some basic items such as bottled water, non-perishable food, first aid kit, a portable radio and other essential items.
  • If a storm is approaching, keep your radio on and LISTEN OUT FOR ALERTS ISSUED BY THE NATIONAL WEATHER SERVICE:Tornadoes rarely appear without warning. They usually come together with severe thunderstorms.
  • A tornado watch is issued when weather conditions are favourable for the development of severe thunderstorms that are capable of producing tornadoes.
  • A tornado warning is issued when a tornado has actually been detected on radar
If threatened by an approaching tornado
INDOORS
  • HEAD TO THE LOWEST LEVEL OF THE BUILDING: If you have no basement, get to the lowest floor of the house or building take shelter in a small inside room near the centre of the house, such as a closet, a bathroom, or under a sturdy desk or table.
  • STAY AWAY FROM OUTSIDE WALLS, WINDOWS AND DOORS: The idea is to put as many walls between you and the tornado as you possibly can, so you will be safe when debri starts being blown at the house.
OUTDOORS
If you are caught outside, get as low to the ground as possible and protect your head from the flying debri. Lie down in a ditch, for example. If you are driving, head away from the tornado’s path and look for a building to shelter in. If the tornado is too close, get out of the car and get down on the ground (In a car is one of the most dangerous places to be)
In the aftermath of a tornado

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